To evaluate the current pneumococcal vaccine in the institutionalized elderly by observing vaccine-associated reactions and subsequent incidence and etiology of pneumonias in pneumonia-associated mortality. A total 1,340 patients, already admitted to 3 different long-term care institutions, received the pneumococcal vaccine. Vaccine-associated reactions overall occurred in 177 (13.2%) of the patients. Acute systemic reactions were noted in 2 (.14%), discomfort in 108 (8.1%), erythema in 70 (15.4%), induration in 32 (2.4%) and fever in 28 (2.1%). Vaccine-associated reactions were significantly more frequent in males than females. Males demonstrated a progressively increasing number of infections from less than 50 years of age (13.0%) to a peak of 60-69 years of age (25.5%). Thereafter, the frequency of reactions decreased in those 70 years of age and older. The same trend was noted for women, although the frequency of reaction was lower. Review of the results for the first 5 months of the surveillance program for pneumonias indicated that radiographically confirmed pneumonias occurred frequently (9-21% of the vaccinated and non-vaccinated population, depending on the institution) but S. pneumoniae was isolated much less frequently than expected (17-30%), and was considered the primary agent in only about 1/3 of the cases. Most of the S. pneumoniae isolates were types or groups not represented in the vaccine, especially in vaccinees. Two cases of pneumonia (both Type 9 and from the same institution), however, did occur in vaccinees who had chronic bronchitis as a predisposing illness.